Gas turbine apparatus



v- 2 1955 L. n. BARRETT, JR., ET AL 2,724,546

GAS TURBINE APPARATUS Filed Aug. 3, 1951 2 Sheets-Sheet l I mm mm mm W JA i OH H T u t N N B m R Dp no I m L M w .m L m Y B OM V mm mm mm mm ow mm Q o g 5 mm mm Nov. 22, 1955 L. D. BARRETT, JR, ETAL 2,724,546

GAS TURBINE APPARATUS Filed Aug. 3, 1951 2 Sheets-Sheet I2 INVENTORS Lawrence D. Barre" Jr John Lippurt ATTORN EY United States Patenr'O 2,724,546 GAS TURBINE APPARATUS Lawrence D. Barrett, Jr., Glenn Mills, and John Lippart, Prospect Park, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 3, 1951, Serial No. 240,212

2 Claims. (Cl. 230-133) This invention relates to axial-flow compressor apparatus and more particularly to a fabricated axial-flow compressor for an aviation gas turbine power plant.

Axial-flow compressor components heretofore proposed for an aviation gas turbine engine have generally comprised a two-piece outer casing consisting of a cover and a base which are bolted together along a horizontal plane, and which contain stationary blading supported .by semicircular shroud elements which are held in place within the outer casing by meansof retaining screws. With this type of compressor casing structure, with non-ferrous alloy construction, high compressor outlet temperatures and pressures tend to make necessary the provision of excessive wall thickness. If magnesium or aluminum is the casing material employed, the high coeflicient of expansion thereof may induce thermal expansion such that blade tip clearance and seal celarance maybe increased under operating conditions, resulting in reduction in compressor efliciency. Furthermore, with a two-piece compressor housing of this type, the provision of a horizontal joint may contribute to distortion of the casing components, induce fatigue failure of the retaining screws, and allow an increased axial deflection of the diaphragm at the horizontal joint with a corresponding undesirable variation in stationary blade stresses in the neighborhood of fifty per cent. i

It is an object of the present invention to provide an improved cylindrical casing and annular diaphragm structure for an axial-flow compressor constructed and arranged to obviate the above-mentioned difiiculties encountered with compressor casings of the two-piece construction.

Another object of the invention is to provide a compressor casing structure including an outer cylindrical shell of steel without any horizontal joints, and a plurality of separately mountable annular diaphragm assemblies which are attached to and stacked within the outer shell during assembly of the compressor rotor discs.

A further object of the inventioin is the provision of an improved cylindrical casing structure of the above character, in which steel or titanium alloy may be employed for high strength under high operating temperatures, the low expansion coefficient of such material rendering feasible the reduction of blade tip clearances.

It is another object to provide an improved casing structure for an axial-flow compressor whichmay readily be assembled with full benefit of the advantages of mass production techniques at low unit cost.

These and other objects are effected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. l is a longitudinal view, partly in section, of an aviation gas turbine engine having a compressor apparatus constructed in accordance with the invention;

Fig. 2 is an enlarged detail fragmentary sectional view of a portion of the compressor shown in Fig. 1;

ice

Fig. 3 is an enlarged detail sectional view taken substantially along the line III-III of Fig. 1;; and

Fig. 4 is a fragmentary perspective view'of a portion of the improved compressor casing structure, with certain portions thereofshown broken away to facilitate understanding of the invention.

Referring to Fig. l, the gas turbine engine therein illustrated comprises an outercasing structure generally indicated at 10, in which is axially disposed a core structure generally indicated at 11, the space therebetween constituting an annular passageway 12 which extends longitudinally through the power plant from a forwardly disposed air inlet opening 13 toa turbine discharge passage 14, it being understood that the discharge passage 14 terminates in a jet nozzle (not shown). Disposed in axial alignment within the casing structure 10 are located the operatingcomponents of the power plant, including a compressor, generally indicated at 16, an annnu lar combustion apparatus 17 and a turbine 18 which is operatively connected to the rotor 19 of the compressor through the medium of a shaft 20. Suitable rotor support means are provided in the casing, including coaxial bearings 21 inwhich is journaled the rotor assembly comprising the compressor, turbine and connecting shaft.

In operation, air" entering the inlet opening 13 is compressed by the compressor 16 and delivered to the combustion apparatus 1'7 for supporting combustion of fuel, which may be supplied by way of nozzles 22, the resultant motive gases being expanded through the turbine 18 and discharged by way of the usual jet nozzle for establish- 3 ing a propulsive thrust.

Referring to the compressor 16 in greater detail, it will be noted that the compressor rotor 19 comprises a plurality of separate discs, such as those indicatedby reference character 25, each of the discs having toothed annular surfaces 26 for interengagement with the complementary surfaces of the adjacent discs during assembly of the rotor. The separate discs 25 are held together by a plurality of axially extending rods 27, which also serve to connect the assembly of discs to the shaft 20. Each of the discs 25 of the compressor rotor carries a plurality of radially extending compressor blades, such as those indicated by the reference character 30.

According to the invention, the compressor further comprises a casing and stationary diaphragm or vane assembly, which includes an outer cylindrical shell 32 having welded to the opposite ends thereof suitable annular flanges 33 and 34 for engagement with, respectively, a flange 35 carried by the forward section 10a of the engine casing structure and a flange ,36 carried by an .intermediatesection 10b of the engine casing structure. The outer shell 32 may be formed of any suitable .material, Such as steel or titanium alloy, as already mentioned. Enclosed within the outer shell 32 are a plurality of annular channel-like diaphragm elements 38, which, as best shown in Fig. 2 of the draw ings, have formed thereon outwardly extending annular flanges 41), the peripheral surfaces of which are adapted to be somewhat spaced inwardly of the inner surface of the cylindrical shell 32. Each of the annular diaphragm elements 38 carries a plurality of radiallydisposed stationary vanes 41, the innermost ends of which are secured to an annular shroud element 42.

It will be understood that each of the separate groups ofradially-disposed stationary vanes 41 will, in practice, be of somewhat different form than the adjacent groups, to constitute successive compressor stages as best indicated in Fig. 1, although the same reference characters a have been applied to all stationary vane assemblies for convenience.

For retaining the annular diaphragm elements 38 in -place, the outer casing shell 32 has secured therein a plurality of longitudinally extending tracks or guide the sides of the guide members 45 engage the sides of the recesses '47, suflicient clearance is provided between the members and the bottom walls of the recesses to allow free radial expansion of'the diaphragm elements 38.

Welded or otherwise suitably secured in the downstream end of the. compressor shell 32 is an annular channel ring 49, against which the first of the series of annular diaphragm elements 38 is adapted to abut when the compressor is assembled. One or more annular shims 50 may, however, be inserted between the lastrnentioned diaphragm element and the abutment channel member 49, if desired. It will be understood that, during assembly of the compressor, each of the rotor discs 25 is adapted to be installed in place between the stationary vanes 41 carried by the respective diaphragm elements 38 of adjacent compressor stages. The step-bystep process of alternately installing compressor discs and diaphragm elements is continued until all of the diaphragm elements are stacked together along the several guide members 45 within the casing shell 32, shown in the drawings.

For holding the last diaphragm element 38 in place at the forward end of the compressor apparatus, an annular retaining ring 52 is provided, one end 53 of the retaining ring being adaptedfor engagement with the forward flange 40 of the diaphragm element, and an outer portion 54'of, the retaining ring being clamped between the flanges 33 and 35, as best shown in Fig. 2.

It will be apparent from the foregoing that a compressor constructed in accordance with the invention will exhibit desirable characteristics of rigidity and freedom from clearance difficulties'due to differential thermal expansion'betw'een the compressor elements, while involving little or no weight disadvantage over casings of twopiece construction as at present employed. Since stresses pressor. The elimination of a conventional two-piece construction renders the casing structure immune to dif fer ential'temperature stresses, since alignment is insured by the engagement of the separatediaphragrn elements on the guide members 45. Furthermore, radial clearance between the slots in the diaphragm outer shroud 47 and the axial tracks 45 will allow free radial expansion, while engagement between the sides of the slots and the axial tracks will permit accurate positioning of the diaphragm in the outer casing.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

What is claimed is:

1. Casing structure for axial flow elastic fluid apparatus comprising an outer cylindrical shell, annular end abutment members mounted in the opposite ends of said shell, a plurality of longitudinally disposed guide elements secured in said shell parallel to the axis thereof, a plurality of integral annular diaphragm elements of the same peripheral diameter, the diameter of said diaphragm elements being smaller than the inner diameter of said shell, said diaphragm elements having recesses for slidably engaging said guide elements, a plurality of circumferentially spaced radially disposed stationary vanes carried in each of said diaphragm elements, and means for clamping said diaphragm elements in stacked relation Within said shell and between said end abutment members.

2. Casing structure for axial flow elastic fluid apparatus comprising an outer cylindrical shell, annular end abutment members mounted in the opposite ends of said shell, a plurality of longitudinally disposed guide elements secured in said shell parallel to the axis thereof, aplurality of integral annular diaphragm elements of the same peripheral diameter, the diameter of said diaphragm elements being smaller than the inner diameter of said shell, said diaphragm elements having recesses for slidably engaging said guide elements, each of said recesses being of greater depth than the portion of the guide element engaged therein to provide radial clearance, a plurality of circumferentially spaced radially disposed stationary vanes carried in each of said diaphragm elements, and means for clamping said diaphragm elements in stacked relation within said shell and between said end abutment members.

References Cited in the file of this patent UNITED STATES PATENTS 917,206 Watts Apr. 6, 1909 2,080,425 Lysholm May l8, 1937 2,247,387 Johnson July 1, 1941 2,427,614 Meier Sept. 16, 1947 2,446,552 Redding Aug. 10, 1948 2,591,488 Yost Apr. 1, 1952 2,592,119 Chilton Apr. 8, 1952 2,649,243 Stalker Aug. 18, 1953 v FOREIGN PATENTS 225,221 Switzerland Apr. 16, 1943 991,982 France June 27, i

OTHER REFERENCES Geist: Abstract Pub. 75,140, February 27, 1951. 

